This invention generally relates to agricultural implements, and particularly concerns a structure and suspension system usable in connection with sprayers and other cantilevered boom structures which extend outward from a vehicle in use, and which are moved over a relatively uneven surface during use.
One of principal applications envisioned for the present invention is the provision of spraying equipment which is readily mounted to a vehicle such as a pickup truck, and which is moveable across an agricultural field to spray herbicide or fertilizer. Spraying equipment of this type typically has a pair of booms, each of which extends laterally outward from the drive vehicle. Each of these booms is typically cantilevered from the drive vehicle. As might be expected, a primary goal of a spraying system is to cover as much area in a single swath as possible. When this is done with a system having a pair of cantilevered booms which hold spray heads spaced along each of the booms, this means each of the cantilevered booms must be as long as possible consistent with proper handling of the vehicle, safety constraints, and the ability of the vehicle to move the booms smoothly across an uneven surface without causing undue movement above the surface.
Individual spraying heads typically have a coneshaped downwardly directed spray. With a number of such spray heads spaced across a sprayer boom at distances such that an even spray without crossover or gaps will normally result, it is essential that the boom typically be maintained at a fairly constant height above the surface to be sprayed. It will be apparent that if the boom is suddenly too low, gaps or unsprayed strips will appear. If the boom is too high, the coneshaped nature of the spray will cause crossover or double spraying in some areas, yet too light a coverage in other areas.
Another constraint faced by a person designing a sprayer is that of protecting the booms against possible impacts. These impacts can occur because the booms are moving forward across a ground surface and inadvertently strike an obstruction, pole, fence post, or other stationary object. These problems can also occur when the mounting vehicle for the sprayer travels over irregularities in the ground surface. Such irregularities can cause the vehicle to tilt with respect to the general plane of the ground surface. Absent some correction system such movement may result in contact of one or both of the booms with the ground surface itself, either causing damage to the boom or sprayer structure or interfering with the crop or soil to be treated.
The invention described in this application is the result of development of a unique structure which provides compensation for uneveness in a ground surface. In addition, due to the construction of the present invention, protection against contact with obstructions encountered by sprayer booms as they move across a field surface is also provided. In addition, the individual booms of the inventive sprayer structure are foldable to be stored in use. While the sprayer of the present invention would function well if mounted on a pickuptruck, it is not limited to such mounting. As shown and described, it may also be mounted by means of a threepoint hitch structure to other agricultural vehicles, and is no sense limited to any particular vehicle.